In recent years, there are mobile terminals such as mobile phones that employ input apparatuses having touch sensors such as touch panels, touch switches, or the like, as input apparatuses such as operation units, switches and the like configured to detect operations by operators. Such input apparatuses having touch sensors are popularly employed not only by the mobile terminals but also by information equipments such as calculators, ticket vending machines, home electric appliances such as microwaves, TV sets, lighting equipments, industrial equipments (FA equipments) and the like.
There are known a variety of types of those touch sensors, such as a resistive film type, a capacitive type, an optical type and the like. However, touch sensors of these types detect a contact by a finger or a stylus pen and, unlike mechanical push-button switches, the touch sensors themselves are not physically displaced when touched.
Therefore, the operator may not be able to obtain feedback in response to an operation to the touch sensor. Since the operator may not be able to obtain an operation sensation “having pressed or released pressing” upon the operation, the operator may not be able to confirm about whether the operation is appropriately detected by the terminal. In using such a terminal, accordingly, the operator is likely to perform a repetitious operation by repeatedly touching the same position, which may be stressful for the operator.
In order to prevent such an unnecessary repetitious operation, there is known a method to generate a sound when the contact to the touch sensor is detected. There is also known a method to change a display state, such as color or the like, of input objects such as input buttons and the like (hereinafter, referred to simply as an “object”) displayed at a position on a display unit corresponding to a position where the contact is detected.
However, such auditory feedback may be difficult for the operator to confirm in a noisy environment and is not applicable when the equipment being used is in a silent mode. Further, through such visual feedback, if the object displayed on the display unit is small, the operator may not be able to confirm a change in the display state, as a view of the object is blocked by the finger, particularly when the operator is inputting by the finger.
In order to deal with such problems, there is suggested a feedback method relying on neither the auditory—nor visual sensation but instead vibrating the touch sensor when the touch sensor detects the contact (for example, see Patent Documents 1, 2).